// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "test.h"

/// This is a test of typical character collision scenarios. This does not
/// show how you should implement a character in your application.
/// Instead this is used to test smooth collision on edge chains.
class CharacterCollision : public Test
{
public:
    CharacterCollision()
    {
        // Ground body
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            b2EdgeShape shape;
            shape.SetTwoSided(b2Vec2(-20.0f, 0.0f), b2Vec2(20.0f, 0.0f));
            ground->CreateFixture(&shape, 0.0f);
        }

        // Collinear edges with no adjacency information.
        // This shows the problematic case where a box shape can hit
        // an internal vertex.
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            b2EdgeShape shape;
            shape.SetTwoSided(b2Vec2(-8.0f, 1.0f), b2Vec2(-6.0f, 1.0f));
            ground->CreateFixture(&shape, 0.0f);
            shape.SetTwoSided(b2Vec2(-6.0f, 1.0f), b2Vec2(-4.0f, 1.0f));
            ground->CreateFixture(&shape, 0.0f);
            shape.SetTwoSided(b2Vec2(-4.0f, 1.0f), b2Vec2(-2.0f, 1.0f));
            ground->CreateFixture(&shape, 0.0f);
        }

        // Chain shape
        {
            b2BodyDef bd;
            bd.angle       = 0.25f * b2_pi;
            b2Body* ground = m_world->CreateBody(&bd);

            b2Vec2 vs[4];
            vs[0].Set(5.0f, 7.0f);
            vs[1].Set(6.0f, 8.0f);
            vs[2].Set(7.0f, 8.0f);
            vs[3].Set(8.0f, 7.0f);
            b2ChainShape shape;
            shape.CreateLoop(vs, 4);
            ground->CreateFixture(&shape, 0.0f);
        }

        // Square tiles. This shows that adjacency shapes may
        // have non-smooth collision. There is no solution
        // to this problem.
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            b2PolygonShape shape;
            shape.SetAsBox(1.0f, 1.0f, b2Vec2(4.0f, 3.0f), 0.0f);
            ground->CreateFixture(&shape, 0.0f);
            shape.SetAsBox(1.0f, 1.0f, b2Vec2(6.0f, 3.0f), 0.0f);
            ground->CreateFixture(&shape, 0.0f);
            shape.SetAsBox(1.0f, 1.0f, b2Vec2(8.0f, 3.0f), 0.0f);
            ground->CreateFixture(&shape, 0.0f);
        }

        // Square made from an edge loop. Collision should be smooth.
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

            b2Vec2 vs[4];
            vs[0].Set(-1.0f, 3.0f);
            vs[1].Set(1.0f, 3.0f);
            vs[2].Set(1.0f, 5.0f);
            vs[3].Set(-1.0f, 5.0f);
            b2ChainShape shape;
            shape.CreateLoop(vs, 4);
            ground->CreateFixture(&shape, 0.0f);
        }

        // Edge loop. Collision should be smooth.
        {
            b2BodyDef bd;
            bd.position.Set(-10.0f, 4.0f);
            b2Body* ground = m_world->CreateBody(&bd);

            b2Vec2 vs[10];
            vs[0].Set(0.0f, 0.0f);
            vs[1].Set(6.0f, 0.0f);
            vs[2].Set(6.0f, 2.0f);
            vs[3].Set(4.0f, 1.0f);
            vs[4].Set(2.0f, 2.0f);
            vs[5].Set(0.0f, 2.0f);
            vs[6].Set(-2.0f, 2.0f);
            vs[7].Set(-4.0f, 3.0f);
            vs[8].Set(-6.0f, 2.0f);
            vs[9].Set(-6.0f, 0.0f);
            b2ChainShape shape;
            shape.CreateLoop(vs, 10);
            ground->CreateFixture(&shape, 0.0f);
        }

        // Square character 1
        {
            b2BodyDef bd;
            bd.position.Set(-3.0f, 8.0f);
            bd.type          = b2_dynamicBody;
            bd.fixedRotation = true;
            bd.allowSleep    = false;

            b2Body* body = m_world->CreateBody(&bd);

            b2PolygonShape shape;
            shape.SetAsBox(0.5f, 0.5f);

            b2FixtureDef fd;
            fd.shape   = &shape;
            fd.density = 20.0f;
            body->CreateFixture(&fd);
        }

        // Square character 2
        {
            b2BodyDef bd;
            bd.position.Set(-5.0f, 5.0f);
            bd.type          = b2_dynamicBody;
            bd.fixedRotation = true;
            bd.allowSleep    = false;

            b2Body* body = m_world->CreateBody(&bd);

            b2PolygonShape shape;
            shape.SetAsBox(0.25f, 0.25f);

            b2FixtureDef fd;
            fd.shape   = &shape;
            fd.density = 20.0f;
            body->CreateFixture(&fd);
        }

        // Hexagon character
        {
            b2BodyDef bd;
            bd.position.Set(-5.0f, 8.0f);
            bd.type          = b2_dynamicBody;
            bd.fixedRotation = true;
            bd.allowSleep    = false;

            b2Body* body = m_world->CreateBody(&bd);

            float angle = 0.0f;
            float delta = b2_pi / 3.0f;
            b2Vec2 vertices[6];
            for (int32 i = 0; i < 6; ++i)
            {
                vertices[i].Set(0.5f * cosf(angle), 0.5f * sinf(angle));
                angle += delta;
            }

            b2PolygonShape shape;
            shape.Set(vertices, 6);

            b2FixtureDef fd;
            fd.shape   = &shape;
            fd.density = 20.0f;
            body->CreateFixture(&fd);
        }

        // Circle character
        {
            b2BodyDef bd;
            bd.position.Set(3.0f, 5.0f);
            bd.type          = b2_dynamicBody;
            bd.fixedRotation = true;
            bd.allowSleep    = false;

            b2Body* body = m_world->CreateBody(&bd);

            b2CircleShape shape;
            shape.m_radius = 0.5f;

            b2FixtureDef fd;
            fd.shape   = &shape;
            fd.density = 20.0f;
            body->CreateFixture(&fd);
        }

        // Circle character
        {
            b2BodyDef bd;
            bd.position.Set(-7.0f, 6.0f);
            bd.type       = b2_dynamicBody;
            bd.allowSleep = false;

            m_character = m_world->CreateBody(&bd);

            b2CircleShape shape;
            shape.m_radius = 0.25f;

            b2FixtureDef fd;
            fd.shape    = &shape;
            fd.density  = 20.0f;
            fd.friction = 1.0f;
            m_character->CreateFixture(&fd);
        }
    }

    void Step(Settings& settings) override
    {
        b2Vec2 v = m_character->GetLinearVelocity();
        v.x      = -5.0f;
        m_character->SetLinearVelocity(v);

        Test::Step(settings);
        DrawString(5, m_textLine, "This tests various character collision shapes.");

        DrawString(5, m_textLine, "Limitation: square and hexagon can snag on aligned boxes.");

        DrawString(5, m_textLine, "Feature: edge chains have smooth collision inside and out.");
    }

    static Test* Create() { return new CharacterCollision; }

    b2Body* m_character;
};

static int testIndex = RegisterTest("Examples", "Character Collision", CharacterCollision::Create);
